Means for regulating the capacity of rotary machines

ABSTRACT

A rotary machine of the sliding vane type has an arrangement for releasing a part of the fluid compressed in the chamber to regulate the capacity of the pressure. This comprises an opening in the wall of the pressure chamber, partially overlying the opening of the cylinder, and a control slide turnably and slidably mounted in the opening. This slide has a passage which is more or less exposed depending on its angular position, the position being controlled by a fluid pressure operated piston. A spring on the opposite side of the control slide from the cylinder pushes the slide toward the cylinder. Under excessive pressure conditions the slide will move away from the wall of the cylinder against the spring and expose the hole of the passage so as to admit full relief of pressure in the chamber.

United States Patent Glanvall [54] MEANS FOR REGULATING THE CAPACITY OF ROTARY MACHINES [72] Inventor: Rune Valdemar Glanvall, Norrkoping, Sweden [73] Assignee: Stal Refrigeration AB, Norrkoping,

Sweden [22] Filed: Nov. 16, 1970 [21] Appl. No.: 89,612

[30] Foreign Application Priority Data Nov. 27, 1969 Sweden ..16371/69 [52] US. Cl ..4l7/310, 417/283 [51] Int. Cl ..F04b 49/00 [58] FieldofSearch ..417/310, 283

[56] References Cited UNITED STATES PATENTS 3,494,288 2/1970 Watson ..417/3l0 X [4 1 Aug. 29, 1972 Primary ExaminerCarlton R. Croyle Assistant ExaminerRichard J. Sher Att0rneyJennings Bailey, Jr.

[57] ABSTRACT A rotary machine of the sliding vane type has an arrangement for releasing a part of the fluid compressed in the chamber to regulate the capacity of the pressure. This comprises an opening in the wall of the pressure chamber, partially overlying the opening of the cylinder, and a control slide tumably and slidably mounted in the opening. This slide has a passage which is more or less exposed depending on its angular position, the position being controlled by a fluid pressure operated piston. A spring on the opposite side of the control slide from the cylinder pushes the slide toward the cylinder. Under excessive pressure conditions the slide will move away from the wall of the cylinder against the spring and expose the hole of the passage so as to admit full relief of pressure in the chamber.

1 Claim, 8 Drawing figures PATENIEUwszs I972 SHEET 1 BF 2 INVENTOR.

SWAN? Ru NE VA LDEM PATENTEDAUGES I972 SHEET 2 [IF 2 Fig. 5'

N EN O K Q'LAN' V'A-LL M MEANS FOR REGULATING THE CAPACITY OF ROTARY MACHINES BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rotary machines, preferably of the sliding vane type, provided with means for regulating the capacity by re-circulating the operating medium. The regulating means permits stepless regulation of the capacity from full power to zero power and also enables a no-load start when the machine is a compressor.

SUMMARY OF THE INVENTION conditions the slide will move away from the wall of the cylinder against the spring and expose the hole of the passage so as to admit full relief of pressure in the chamber. The regulating means is particularly suitable for rotary machines of the sliding vane type, having a small number of vanes and suitable positioning of a control slide results in efiicient regulation, i.e. little power loss.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in the accompanying drawings where FIG. 1 shows a cross-section through a rotary compressor. FIG. 2 shows a longitudinal section along the line II II in FIG. 1. FIG. 3 shows a crosssection along the line III IH in FIG. 1 and FIGS. 4 7 show cross-sections of various regulating positions. FIG. 8 shows an end view of a regulating slide.

DESCRIPTION OF THE PREFERRED EMBODIMENTS l designates a rotor located in the housing 2 of a compressor, and 3 is the vanes. At one or both sides there is a control slide 4 which can be turned and has an axially running re-circulation channel 5 which conmeets a high pressure chamber 6 in the compressor with a chamber 7 on the other side of the control slide, this chamber being in connection with the suction side of the compressor either directly or through a channel 8. Control slide 4 is turnable in an opening which overlaps the compression chamber only in part.

A spring 9 balances the control slide against the pressure in the chamber 6 by way of a pressure plate 10 and ball 1 1 and assures that there is always contact between the housing 2 and the control slide. 12 designates a channel in the plate 10 to equalize the pressure on either side of the plate.

The desired control position is set with the help of a control piston 13 which is actuated by pressure oil, for example from an oil pump 14 (FIG. 4). The oil flow is regulated by a valve 15 controlled by a sensing body 16 which is influenced by temperature or pressure in an eva rator elo n to a ooli s stem. 17 desi g nates a rot ig point for oil whiz: is ed away to anoil sump.

The control piston 13 is connected to the control slide 4 by means of a rack gearing 18 in engagement with a toothed rim 19. The linear movement of the piston 13 may of course be converted to the turning movement of the control slide in some other way, for example by means of a link system. The pressure on the piston is balanced by a spring 20. The regulating slide may even be manually controlled or controlled by means of a turning mechanism built into the slide.

The hatched part in the compressor according to FIGS. 4 7 indicates the pumped operating medium. FIG. 4 shows the slide 4 turned for full power, as there is no re-circulation. FIG. 5 shows maximum partial power, FIG. 6 shows increased re-circulation and thus less partial effect, and FIG. 7 shows minimum partial power.

The control range is determined, inter alia, by the number of vanes the machine has, the position of the control slide in relation to the high pressure channels 21 of the machine and the relationship between the diameters of the rotor, the housing and the control slide. In principle a control slide with large diameter has a large control range.

In multi-chamber machines one or more chambers can be provided with the means according to the invention, depending on the desired degree of unloading.

The control slide also functions as an extremely effective safety valve against hammering, since at high pressure in the chamber 6 it opens the re-circulation channel 5, the spring 9 being compressed and the control slide 4 being moved axially so that liquid also flows to the suction side through the channel 8. The system has the same function if the pressure on the operating medium is too high, and the slide 4 thus acts as a safety valve. This is because, even if slide 4 is in the position shown in FIG. 4, sufficient pressure in chamber 6 will push it to the right (FIG. 2) against the action of spring 9, thereby allowing fluid to flow through the whole area of passage 5.

The invention has been described as used in a compressor, but it may also be used in a motor.

I claim:

1. In a rotary machine having walls forming a compression chamber, input and output openings in said walls, means for regulating the capacity of the chamber comprising means to release a part of the fluid compressed in said chamber, said releasing means comprising a release opening in a wall of the chamber at a point between said input and said output openings, a control slide turnably and slidably mounted in said opening and having passage means connecting said release opening to said input opening, said slide providing varying degrees of communication with the opening in different angular positions of the slide, regulating means controlling the angular position of said slide, and spring means acting on the other side of the slide from the chamber acting on the slide to counteract the pressure of pressure fluid in the chamber. 

1. In a rotary machine having walls forming a compression chamber, input and output openings in said walls, means for regulating the capacity of the chamber comprising means to release a part of the fluid compressed in said chamber, said releasing means comprising a release opening in a wall of the chamber at a point between said input and said output openings, a control slide turnably and slidably mounted in said opening and having passage means connecting said release opening to said input opening, said slide providing varying degrees of communication with the opening in different angular positions of the slide, regulating means controlling the angular position of said slide, and spring means acting on the other side of the slide from the chamber acting on the slide to counteract the pressure of pressure fluid in the chamber. 